Bond pads are used to electrically connect a semiconductor die to a packaging terminal interconnect. A packaging terminal interconnect may be a lead, ball, no lead, combinations of the above or the like. It is important that the signals sent between the semiconductor die and the packaging terminal interconnect are reliable. Much of this depends on the bond pad structure.
Currently, aluminum bond pads are used in much of the industry. Typically, a metal layer of approximately 6,000 Angstroms of aluminum is deposited and patterned as the last metal line in a semiconductor die fabrication process. A passivation layer is formed and patterned over the metal layer. During patterning of the passivation layer, the thickness of the aluminum bond pad can be significantly reduced. The resulting thickness of the metal layer (approximately 1,000-2,000 Angstroms) is too thin to provide adequate electrical reliability.
One proposed solution is to form a TiN layer over the aluminum bond pad to prevent the thinning of the aluminum during processing. However, the TiN layer must be removed prior to bonding in order for the aluminum bond pad to be electrically coupled to the packaging terminal interconnect. However, current TiN dry etch processes attack the underlying metal layer. Thus, the metal layer is thinned during removal of the TiN layer and reliability is poor. Therefore, a need exists for a process that does not thin the metal layer and thus, increases reliability between the semiconductor die and the packaging terminal interconnect.
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